CAVEAT User Guide


1.0 Software and Platform Recommendations

Mozilla Firefox is the recommended and tested browser for using CAVEAT. The website has yet to be customized for other browsers and as such may distort webpage styling. Where required press the "ctrl" and "+" key to zoom in and improve viewing.

CAVEAT is primarily a server-hosted entity, meaning that all user interaction is done online. However, to assist spatial orientation and visualization all map products are overlain on a Google EarthTM globe. As a result the user is required to download the Google EarthTM plug-in, available online at: http://www.google.com/earth/explore/products/plugin.html.


1.1 Loading the Website with a Browser

The website home page URL is www.mycaveat.com. Here, the Climate Change and Agriculture Visualization and Estimation Analysis Tool is introduced, outlining its overall objectives and providing a brief orientation for new users (e.g., Figure 1).

Figure 1. CAVEAT home page with Start the Model button indicated.


1.2 Specifying Inputs to be Visualized

The user proceeds by pressing one of the Start the Model buttons found on the home page, e.g., main navigation bar circled in Figure 1. This loads the model input page where customization of the map output is initially declared. The user is required to first specify a path of future global development ranging from a high growth, mid growth, or low growth scenario; the selection of a wet, mid, or dry atmosphere-ocean general circulation model (AOGCM) from which climatic projections will be made; a time period in the future for indicator variable estimation (2020, 2050, or 2100); the desired display variable or map output; and finally make a declaration to display either baseline (1961 – 1990), future (user specified Time Horizon), or change from baseline (the difference between the two products) found under the specification drop-down menu. Figure 2 depicts the input menus screen.

Figure 2. CAVEAT model input page with Run the Model button indicated.

On this page, the user is presented with a form of five drop-down menus. Note that not all options are selectable. This is because CAVEAT currently supports only the “A1B” forcing/emission scenario of future global development; the Geophysical Fluid Dynamics Laboratory (GFDL) “CM2.1” AOGCM climate simulator; the 2050 time horizon; Temperature, Precipitation, and Maize yield variables; and Baseline, Future, or Change specifications for on screen map output display. Other options have been coded into the menus and are intended for future expansion of the model.

Please note that Maize yields are only available for display on a future specification, baseline and change Maize yields are not currently supported.

The user proceeds by making a selection for all menu inputs and pressing the Run the Model button as indicated in Figure 2. This sends a Hypertext Preprocessor (PHP) – Structural Query Language (SQL) query to a PostgreSQL database and loads the model output page with the relevant data.

For more information on forcing/emission scenarios and/or atmosphere-ocean general circulation model selection please refer to the Background Information page located in the help drop down menu.


1.3 The Model Output Page

The central feature of the Model Output page is an instance of the Google EarthTM plug-in (e.g., Figure 3).

Figure 3. CAVEAT model output page with change from baseline surface temperature displayed.

Displayed immediately beneath the top navigation toolbar is the user specified model inputs; missing input errors will also be displayed here. Below this is the main Google EarthTM mapping instance where the model results will be displayed.

A legend appears on the bottom-left of the plug-in. The Google Earth navigation controls appear on the right. The larger top button (having “N” at top centre) controls the rotation, angle and pitch of the view in the plug-in. The middle button enables the user to pan across the image. Finally, the vertical slider controls the zoom. The user zooms in either by pressing repeatedly on the “+” end of the control or by dragging the handle up the slider. Zooming out is achieved by pressing “–” repeatedly or by dragging the handle down the slider.

Upon loading, the plug-in is programmed to display the user’s overlay as large as possible within the map instance. From here, the user may wish to isolate and view a study location by querying the Google EarthTM place names database. The Type Location input field and Fly Here! buttons accommodate this functionality. The input field accepts place names and addresses in the same format possible with Google Maps.

Having subsequently panned zoomed and tilted to a different position from the initial load, the user may wish to run the model with new inputs and preserve this custom view. In this case, the user presses the Set Study Area button below the plug-in on the left (Please note: this process is required before each new map output declaration, otherwise the display will default to the initial extent). To set the view back to default from a custom zoom, the user presses the Initial Extent button.

The drop-down menu controls from the model input page are also provided below the map plug-in allowing the model to be re-run from this screen. If the user does not make a valid selection (i.e., does not select a variable from each of the 5 dropdown-menus, or attempts to display either baseline or change maize yield maps) and then clicks Run the Model, an alert message appears and no map is loaded (e.g., Figure 4). Again, information on specific variables not input are subsequently displayed below the main navigation and above the Google EarthTM instance.

Figure 4. CAVEAT model output page with incorrect selection alert message.

To assist visualization, at the bottom-right below the Google EarthTM instance are controls for customizing the map output display, namely: road features, border features, and the mapped variable itself. The visualization of roads and borders are activated as the user zooms closer to the Earth. These display features along with the mapped variable may be turned on or off via checkbox control switches. Note, turning off the mapped variable layer also hides the legend. Highlighted in Figure 5 an opacity slider has also been included. This allows the user combination views of land-cover and the mapped variable, assisting user analysis and navigation. Initially, all overlays are loaded at full opacity; dragging the slider to the left makes the overlay and legend transparent (e.g., Figure 5).

Figure 5. CAVEAT model output page with change from baseline surface temperature displayed at 45% opacity.

For additional information please refer to the Background Information page or contact the developers directly.


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